Lemma 6.45 (See [1]}.) 
 Referring to Notation REF ,
\(a_0 &= \theta _0 + \frac{\varphi _1}{\theta ^*_0 - \theta ^*_1}, \\a_i &= \theta _i + \frac{ \varphi _i }{\theta ^*_i - \theta ^*_{i-1} }+ \frac{ \varphi _{i+1} }{\theta ^*_i - \theta ^*_{i+1} } && (1 \le i \le d-1), \\a_d &= \theta _d + \frac{\varphi _d}{\theta ^*_d - \theta ^*_{d-1} }. \) 

